Field experiments were conducted for two seasons to study the physiological responses to varying plant populations and row spacings of rice and corn in monoculture and intercrop plantings. The lowering of dry matter production of rice over the entire growing period in intercrops having high corn population was evidenced through decreasing LAI, NAR, RGR, CGR, and RLGR. LAR increased. Intercrops with corn suppressed the growth of rice probably through shading and competition for growth resources.